If you love sweet peas, then it’s MORE than worth sowing some in the autumn. They will be stronger, beefier and flower earlier than if you sow in the spring. You can totally buy autumn-sown sweet peas too, but I do find that they suffer somewhat in transit, which is why I prefer to sow my own. Here is how I do it.
…and here are some written instructions too:
Find a packet of seeds. I’m not going to faff about recommending varieties here - it’s very personal - but I would say that if you are going to the effort of growing them, then you’re going to want the strongest scented ones possible. I have yet to meet anyone who didn’t love the scent of sweet peas.
Soak your seeds in warm water overnight. I have no idea whether this ACTUALLY helps germination, but I do it anyway because it’s an easy step and there’s nothing to lose.
Prepare your containers. I like to sow my sweet peas singly which makes them easy to plant out in spring. I use rootrainers (which I bought many years ago and are still just about holding together. I also use old loo rolls.
Fill your containers with a free-draining compost. I use multi-purpose compost mixed about two-thirds to one third with perlite or grit. Make sure you tap the compost down into the container so there aren’t any huge air pockets, and water everything thoroughly.
Sow your seeds, one per container by sticking your forefinger into the soil up to the first knuckle and putting a seed into each hole. Cover them up with soil and put the tray of pots in your kitchen to germinate. I like to use a tray with a plastic lid to keep the air moist but this is not essential.
Once the seeds have mostly germinated remove any lid that you’re using, put a kebab stick into each cell (you’ll eventually tie your peas to these for support) and start hardening your seedlings off. These little babies can stay outside over the winter, as long as you have some kind of protection from the elements in place. I use a cold frame, or a clear plastic storage container with lid. For the first few days I put them outside during the day with the lid ajar, then I put them outside at night with the lid on, and after a couple of weeks I leave them open to the elements, unless rain or snow or high winds are forecast. The important thing is to keep them cold, so that they grow up strong. Tie the stems in gently and loosely with string once they are tall enough.
At some point (probably around January or February) I’ll pinch out the tips of my sweet peas. This means removing the top two leaves of the central (main) stem in order to encourage side growth. This will give you two shoots rather than one, (AND DOUBLE THE FLOWERS).
In the spring, once you get around to it, prepare your ground (or if your’e like me, large containers) with really nutrient-rich compost (I use multi-purpose mixed half and half with manure) and plant your seedlings out. You’ll need to give them something to climb up and then you’ll be away.